1. Field of the Invention
This invention relates to a disk drive suspension comprising a microactuator element of, for example, lead zirconate titanate (PZT).
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus, such as a personal computer. The HDD comprises a magnetic disk rotatable about a spindle, a carriage turnable about a pivot, etc. The carriage, which comprises an actuator arm, is configured to be turned transversely relative to tracks of the disk about the pivot by a positioning motor, such as a voice coil motor.
A suspension is mounted on the actuator arm. The suspension comprises a load beam and flexure superposed thereon. A slider, which constitutes a magnetic head, is mounted on a gimbal portion formed near the distal end of the flexure. The slider is provided with elements (transducers) for accessing data, that is, for reading or writing data. The load beam, flexure, slider, etc., constitute a head gimbal assembly.
In order to overcome the increase in the recording density of disks, the magnetic head should be more precisely positioned relative to the recording surface of each disk. To attain this, dual-stage-actuator (DSA) suspensions have been developed that combine a positioning motor (voice coil motor) and microactuator element made of a piezoelectric material, such as lead zirconate titanate (PZT).
The distal end of the suspension can be quickly moved by an infinitesimal distance in a sway direction (or transversely relative to tracks) by applying a voltage to and thereby deforming the actuator element.
As disclosed in Jpn. Pat. Appin. KOKAI Publications Nos. 2003-059219 (Patent Document 1) and 2010-146631 (Patent Document 2), moreover, there are known DSA suspensions in which a microactuator element is disposed on a gimbal portion of a flexure.
A microactuator disclosed in Patent Document 1 is called a piggyback microactuator. In the piggyback microactuator, a microactuator element of PZT or the like is superposed on the back surface of a slider. In this case, the thickness of the microactuator element is added to that of the slider. Therefore, the thickness of a head portion of a head gimbal assembly increases, making it difficult to reduce the thickness of a disk drive. In some piggyback microactuators, a load caused by a mechanical shock, if any, applied to the head gimbal assembly may act on the slider and the microactuator element. Thus, microactuator elements of a fragile material such as PZT are liable to be broken.
On the other hand, a microactuator disclosed in Patent Document 2 comprises a microactuator element secured to one surface (facing a load beam) of a tongue and a slider secured to the other surface of the tongue. In the case of this microactuator, the distal end of a dimple formed on the load beam contacts the one surface of the tongue. It is necessary, therefore, to make the thickness of the microactuator element smaller than the projection height of the dimple. Accordingly, there is a problem that microactuator elements of a fragile material such as PZT are easily broken.
Further, a conductive circuit portion of a conventional DSA suspension easily swings, since it is disposed externally bypassing a pair of microactuator elements. In this case, the conductive circuit portion flaps as the driven microactuator elements vibrate, and a gimbal portion is inevitably influenced by the vibration. As a slider is pivoted by the microactuator elements, moreover, the conductive circuit portion is tensioned because of its large amount of movement, thereby possibly hindering the pivoting motion of the slider. If a part of the conductive circuit portion is disposed near the microactuator elements, furthermore, the fragile microactuator elements may be broken when contacted by the conductive circuit portion.